I've been flying with American for the last 20 years, collecting almost 1.5 M miles, and last week I was offered an double op-up, when returning from IAH to EZE.

When I arrived to the airport I found that the flight from IAH to DFW was cancelled and my trip was rerouted through MIA. While I was checking in, the lady doing the check in for me suddenly mutters "what is class R?". Immediatly I smiled as I knew it was an upgrade, but I never expected the seat I saw on the leg MIA-EZE as it was in First... sweet!

Given that the original seat from DFW to EZE was in the back of the plane in the middle of the 5 seat row, was a very nice upgrade!

Javier